Gliederung

Objective

The infection of the cornea with herpes simplex virus-1 (HSV-1) can induce an immunopathological disease termed herpetic stromal keratitis (HSK). Proinflammatory cytokines like interferon-gamma (IFN-γ) are known to be involved in the development of this disease. In this study antisense oligonucleotides (ASON), that were complementary to IFN-γ mRNA, were proven for their activity in a murine model of HSK.

Methods

Splenic cells of infected mice were used to scrutinize the efficacy of ASON in vitro by measurement of the IFN-γ content in cell culture supernatants by ELISA. At day 0 mice were corneally infected with 105 PFU HSV-1. ASON were given subepithelially at days -1, 1 and 4. The animals were followed up daily for the development of HSK. The mice were sacrificed on day 14 and 28 and the eyes were histologically examined. In order to examine infection as well as substance- and treatmentspecific bystander-effects control groups of mice were only infected or treated with unrelated control oligonucleotides (CON) or buffer respectively.

Results

In vitro ASON reduced the content of IFN-γ in dependence of the concentration while CON showed only slight effects. In vivo, cases of severe keratitis including ulceration and corneal perforation were prevented by treatment with ASON. In contrast, approximately one third of the mice in control groups showed that strong degree of HSK. The incidence of the disease was also clearly diminished after application of ASON. Two weeks post infection the number of inflammatory cells in both the central and the peripheral cornea were strongly reduced after ASON treatment when compared with the controls. These differences were clearly visible as late as four weeks after infection when the cell counts as a whole were lowered. After injection of CON or buffer the clinical and histological parameters were not found to be significantly altered.

Conclusions

Specific ASON targeting IFN-γ ameliorated the course and incidence of HSK in the murine model. Simultaneously the development of severe cases was prevented. IFN-γ seems to be involved in the development of HSK.